cirsgsfc 1 composite infrared spectrometer marcia segurapaul romani shane albrightvirgil kunde ray...

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CIRSCIRSGSFCGSFC

COMPOSITE INFRARED SPECTROMETER

Marcia Segura Paul Romani

Shane Albright Virgil Kunde

Ray Ferrer

CIRS FLIGHT SOFTWARE

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CIRSCIRSGSFCGSFCOVERVIEW

Flight software consists of two parts– Command executive (version builds if major, point builds for

patches)• Instrument operation• Signal and data processing• Packetization

– Command sequence tables (point builds)• Two types of tables: functional and look–up table• A functional table is a set of instrument commands, • Each functional table performs a specific task, e.g.

– Perform a calibration– Set instrument observing mode: spectral resolution, pixel selection, data

rate, etc.– Diagnostic memory dumps– Etc.

• Look–up table: table of memory addresses of functional tables

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CIRSCIRSGSFCGSFCWHERE WE ARE – 1

Last time we met:– We were flying version 1.2/2.0.1– Needed to be upgraded before tour

• Executive: Important features needed for ease of use in tour operations

• Tables: Loading of “Lego” tables (310!)

Version 3.0.0 required changes to project software

This in turn required much– Screaming– Yelling– Loss of vacation time

Version 3.0.0 officially delivered in October of 2003

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CIRSCIRSGSFCGSFCWHERE WE ARE – 2

Version 3.0.0 status– Tested on the spacecraft 15–17 December 2003– Passed all tests– Has been used during approach science– Will be used in tour until probe release– So far have discovered two “undocumented features”

• One required an immediate fix (done last week)• The other we are waiting to fix with 4.0.0

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CIRSCIRSGSFCGSFCWHERE WE ARE GOING – 1

Version 4.0.0 new features of interest to science:

– Timed Table CommandThe command would start a table executing but terminate it after a specified time.

– Blink CommandUpon receipt of this command CIRS would start the scan mechanism and take alternate interferograms of (FP3EVEN,FP4ODD), (FP3ODD,FP4EVEN) of the desired scan length co–adding or not as requested.

– Flush Time Tagged Command Buffer CommandA command to flush all commands from one or both of the time tagged buffers. Optional table termination as well (all or part of the table nesting).

– Ability to recycle tablesAdd the ability to save tables currently located in memory to an internal library or to copy data from 1 table number to another. An alternative would be to create a separate internal command used to point table x to the location of table y so that there would be no need to even have the duplicate data in memory.

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CIRSCIRSGSFCGSFCWHERE WE ARE GOING – 2

All of these changes will be done to CIRS internal commands

Why?

Does not require changes to project software or:– Screaming– Yelling– Loss of vacation time

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CIRSCIRSGSFCGSFCBACKUP MATERIAL 2.0 CHANGES

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CIRSCIRSGSFCGSFCCHANGES TO EXECUTIVE FOR 2.0 – 1

Added nested loop capability to tables– Learned from Jupiter that loops within loops are a very efficient

way to construct science sequences– Previous version of flight software did not permit this

Focal plane 1 bias adjusted– Offset bias is subtracted from the FP1 signal onboard– Improves effect of onboard data compression algorithm– We are currently patching this every time the flight software is

loaded– New software removes need for patch

Allow CIRS to be muted and un–muted via BIU– Needed for CIRS to be on and in sleep mode for probe checkouts– Previous version CIRS would not respond after being un–muted

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Added unique flight software version identifier – In response to request from project– Aids CDS in verifying successful upload of flight software to the SSR

Increased limit for number of tables– Old limit was 256 (includes look–up table)– Scoping for tour operations indicated needed more tables– New limit is 512 (includes look–up table)

Added capability to independently read–out focal planes– CIRS has three focal planes to span the IR:

• Single detector in the far IR• Two 1×10 arrays in the near IR

– Previous flight software got data from either all focal planes or none

– Not reading out one of the mid IR arrays, when scientifically justified, helps to reduce SSR data overload and DSN downlink bottleneck

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Modified CIRS load command sequence table command – Two goals:

• Make flight software more resilient to errors in table load process• Gain insight into table load process

– Flight software now buffers incoming tables and performs the following integrity checks:• Table does not fit in allotted space• Too many words received• More than one table load at a time• Table checksum does not match• Packet sequence is incorrect

– If the table passes these checks it is loaded into CIRS memory– If not, a dummy table is loaded in place of the failed table– When CIRS table load commands are sent as direct packets

simple resending of dropped packet will not work

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Modified CIRS load command sequence table (cont.) – Send status bits down in existing spare HK telemetry channels:

• Table number• Calculated checksum• Received words.

– Flight software buffers table load status/error bits so that they come down one per HK packet in case of multiple errors

Increased upper limit of software watchdog timer– The software watchdog timer verifies that the flight software is

operating within its boundaries– The new flight software build larger than previous build– Therefore the upper limit of the software watchdog timer was

increased

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Increased size of CIRS instrument memory allocated to command sequence tables

– Flight software executive controls how much of CIRS instrument memory is allocated to tables

– We are currently patching (increasing) this number every time the flight software is loaded

– Added this patch to the new build so patches are no longer necessary

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CIRSCIRSGSFCGSFCSUMMARY OF CHANGES TO TABLES FOR 2.0

Changes to SCI_SCAN command in new software required changes to all tables that used this command

Last major update to tables was for version 1.2.0

Used this to critically review and scrub tables based upon Jupiter experience

New flight software loads 51 tables (table numbers 0–50) along with the executive

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CIRSCIRSGSFCGSFCBACKUP MATERIAL 3.0 CHANGES

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CIRSCIRSGSFCGSFCSUMMARY OF CHANGES TO EXECUTIVE FOR 3.0

Increase number of table numbers to 1024 Increase time delay for relative time tagged commands Changes to table load command

– Increase number of hex data words allowed– Identify source of CIRS table load command (from SSR or SASF)– Correct bad table rejection procedure

Decrease loop count value Definition/redefinition of some telemetry channels

– Added number of pending absolute time tagged commands into housekeeping

Allow looping over tables Allow absolute time tagged commands in a trigger sequence

list

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Increase number of tables from 0 – 511 to 0 – 1023

Reason for change– It has been determined that on average for tour operations CIRS

needs 600 table numbers on board the spacecraft at all times• Tables 0 – 100 Engineering and calibration tables• Tables 101 – 450 Set instrument observing mode• Tables 451 – end Trigger tables (call tables 101 – 450)

– Trigger tables• CIRS needs a unique trigger table for each observation• there are on the average 150 CIRS observations per tour sequence• Must have valid trigger tables for sequence n and n+1 to handle

sequence boundary properly• Therefore need 300 trigger tables

– Therefore need table numbers 0 – 750 (average)– Going to 1024 (next power of 2) allows for margin and

deviations from average

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Increase relative time delay from 2 hours 16 minutes 32 seconds to 72 hours 49 minutes 4 seconds

Reason for change– CIRS trigger command operations

• Single trigger from spacecraft sequence sent to CIRS• This trigger command populates a relative time tagged command

buffer with other trigger commands (can hold 256 pending commands)• Relative execution time of the trigger commands in the command

buffer comes from the relative time delay within the trigger command• Execution of trigger commands synched to the pointing design

– With version 2.0.1 cannot command CIRS past 2 hours with a single trigger command

– Most observations/requests last longer than 2 hours– Maximum possible time for observation is 48 hours

(Require DSN pass to empty SSR)– Therefore new design is robust

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Increase maximum number of hex data words in a table load command from 24 words to 113 words

Reason for change– CDS created library region on the SSR for instruments to store

IEBs– Memory is segmented into 128 word chunks– CIRS has been allocated 96 128–word segments– Only one load command can be stored per segment– More efficient use of SSR library segment (25% vs. 100%)

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Version 3.0 adds a source parameter field to the table load command where:

– Value = GND means table load command is from ground (SASF)– Value = SSR means table load command is from the SSR

Reason for change– Two goals:

• Desire to increase number of hex data words in load command to better use SSR library region

• Desire to minimize changes to F S/W code that performs error checking of load commands

– Goals met by addition of this parameter to the load command

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CIRS performs error checking of table (IEB) load commands– IEB fits within allocated memory– Received words matches expected words– Packet continuity – Etc.

If a table (IEB) fails any one of these tests then– Error bits are set in housekeeping– Dummy table loaded in place

Version 3.0 corrects two problems in this function in 2.0.1– No dummy table loaded if START packet missing– If table being loaded was the look–up table, it would be

overwritten with a dummy table

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Decrease maximum number of times a table may be “looped over” from 65,635 to 32,767

Reason for change– CIRS F S/W documentation states that one 16–bit word is

allocated for loop count– CIRS operations assumed that full word was available or

maximum loop count is 65635– Testing for tour operations showed that if all 16 bits were used F

S/W treated loop count as a negative number

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In version 2.0.1 when a table calls a table, commanding terminates in the table that is called

In version 3.0 when a table calls a table, commanding returns to the calling table once table called has completed

Reason for change– Allows for looping over tables– Useful in constructing CIRS mapping sequences

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Version 2.0.1 only allows for absolute time tagged trigger commands to be placed in the absolute time tagged command buffer via individual commands

Version 3.0 allows for absolute time tagged trigger commands to be placed in the absolute time tagged command buffer via trigger sequence lists (table of table calls that places the tables into a command buffer).

Reason for change– Allows for a single trigger command to populate the absolute

time tagged command buffer– Reduce number of CIRS trigger commands in background

sequence

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CIRS has two pending command buffers– Number of relative time tagged pending commands, maximum

256– Number of absolute time tagged pending commands, maximum

64– Currently number of all pending time tagged commands is

returned in housekeeping word 30 and displayed as one channel– Split word into two channels:

• Number of relative time tagged pending commands • Number of absolute time tagged pending commands

– Improved insight into status of CIRS command execution– Improved anomaly diagnosis and response

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CIRSCIRSGSFCGSFCSUMMARY OF CHANGES TO TABLES FOR 3.0

Cleaned up version 2.0.1 tables and modified as needed to work with 3.0

Added 310 basic CIRS tour operational tables

cirsgsfc 1 composite infrared spectrometer marcia segurapaul romani shane albrightvirgil kunde ray...

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